Timing apparatus



Jl me 26, 1951 w. R. HEWLETT ET AL TIMING APPARATUS Filed Oct. 24, 1949 PIE E PIE E lNVENTORS FILE 1407015307 2. eW/eff Packard ATTORNEYS 5 Patented June 26, 1951 TIMING APPARATUS William R. Hewlett, Palo Alto, and David Packard, Los Altos, Calif., assignors to M. P. H. Industries, Palo Alto, Calif., a corporation of California Application October 24, 1949, Serial No. 123,255

8 Claims. 1

This invention relates generally to timing apparatus such as is useful for producing one or more responses in predetermined timed relation to an actuating signal.

In the past various types of timing devices have been used for securing one or more responses in predetermined timed relation to receipt of a controlling signal. For example it has been proposed to employ a simple type of electrically energized perforating device which serves to apply perforations in a continuously moving paper tape. The tape in turn moves continuously past one or more sets of electrical contacts which are operated according to the positioning of the perforations. The rate of movement of the tape and the spacing between the perforating device and the contacts serves to determine the time interval between receipt of a signal and operation of the contacts. Another type of timing device is shown in Marihart 2,437,168, in which a plurality of mechanical lugs are frictionally retained upon the periphery of a wheel, and are released by receipt of a signal to move with the periphery of the wheel. One or more switches are placed in the path of movement of the lug whereby they operate at predetermined intervals following the release of the lug.

Timing devices of the type described above, and other devices which are available for this purpose, are subject to a number of disadvantages. In particular they have been complicated with respect to the mechanical elements employed, and they have been subject to inaccuracies in the timing provided. In addition they have not been well adapted for high speed operation.

It is an object of the present invention to provide novel timing apparatus which will utilize a minimum of mechanical parts, and which will make possible delayed timing to a high degree of accuracy.

Another object of the invention is to provide timing apparatus of the above character which can operate at relatively high speeds, and which when so operated is not subject to serious mechanical deterioration.

Another object of the invention is to provide apparatus of the above character in conjunction with novel circuit means characterized by provision for continuing energization of a magnetizing device after receipt of a signal, and for automatically rearming the circuit means.

Additional objects of the invention willappear from the following description in which the preferred embodiments have been set forth in detail in conjunction with the accompanying drawin Referring to the drawing:

Figure l is a diagrammatic view illustrating the present invention, and incorporating circuit means of the relay type.

Figure 2 is a view like Figure l but illustrating a modification of the invention in which the circuit means includes electronic amplifiers.

Figure 3 is a view like Figure l but illustrating another embodiment of the invention in which a special type of electronic circuit means is employed.

Figure 4 is a diagrammatic view like Figure 1, but illustrating another embodiment of the invention which incorporates the electronic means of Figure 3, together with additional automatic means for insuring rearming of the circuit.

Figure 5 illustrates another circuit which can be employed to perform the essential functions of the circuit shown in Figure 4.

Figure 6 is a side elevational view showing suitable mechanical details for a portion of the invention.

In general the present invention employs a movable member formed of magnetizable material, in conjunction with an electromagnetic device which is adapted to be energized to effect local magnetization of the member, and one or more electromagnetic pickup devices. The rate of movement of the magnetizable member, together with the spacing between the electromagnetic devices, determines the time interval between receipt of a signal to cause a magnetizing effect, and receipt of a response by the electromagnetic pickup means.

Referring first to Figure 1 of the drawing, we have shown a magnetizable member l0 which is movable at a continuous speed and which for example may be in the form of an endless tape, drum, or disc. It is of such construction that it can be magnetized in a localized area with retention of such local magnetization until magnetically erased. It is satisfactory to use relatively thin carbon steel, as for example sheet steel ranging from say 0.003 to 0.006 inch in thickness,or we may employ surface coating of magnetizable material, such as finely divided magnetizable material, applied to a base material which is nonmagnetic. As diagrammatically illustrated in Figure 1 it is assumed that the member I0 is the peripheral margin of a disc or wheel.

At one point along the path of movement of the member In there is an electromagnetic device I l which is adapted when energized to effect local magnetization of the member ID. Electromagnetic pickup devices I2 and l 3 are also shown, and

beyond the pickup device l3, there is a magnetic eradicating device [4. Device l4 can be placed a short distance in advance of the electromagnetic device I l.

Each of the devices ll, l2 and I3 are diagrammatically illustrated as including a magnetic core, together with a winding. The pole pieces of the cores are arranged inclose proximity with one side of the member ID. Eradicatin device 14 can be a simpl permanent magnet, or an electro.-' magnet continuously excited with alternating, current.

In the embodiment of Figure'rcircuitmeans of the relay type is used in conjunction with the electromagnetic device H, and. the pickup'device l2. Thus the circuit means includes a relay 16 having two sets of contacts landv 2, and the-two windings 3 and 4. The winding 4 connects with an input circuit ll, upon which a signal or-actuating pulse is applied. The winding 3 is included in a holding circuit l-B', which includes the contacts-2, the contacts :5 of a relay l9, and the battery or" source of current 20. The contacts I are included in an energizing circuit 2| for the device H, and-which includes the battery'22 or other'source of current. Contacts I and 2 are normally opened, while contacts Earenormally closed.

Assuming'that. current is applied to the-winding-4 of the relay t6, contacts-land 2 are closed to energize the device I l. The closing of holding contacts '2 closes'the'holding circuit I'B, so that thereafterboth'contacts l and Z remain closed, irrespective of discontinuanceof current applied to the windingw. Thescircuit i now disabled in that it willrnotfrespond to receipt of ranothersig- 1131.. until rearmed. :Energization ofthe electromagneticdevicel I-causesv creation of an intense localized magnetic field, the flux-path of which includesaportionof-the.-.-member I0, whereby a loealizedarea of. this memberis permanently magnetized. Assuming that the member l0 moves at aconstant. speedwhile the devicel lcontinues to be energized, themagnetization will continue. for an:- extendedarea until device i lis de-energized. As theadvancing end of the magnetized area passes the electromagnetic pickup device [2, a current :is induced in-the winding ofthe same which-energizes relay- Hi to open the contacts -5. This serves-to-open the holding circuit I 8,.thus de energizi-ng winding 3, and. permitting the contactsland-2 of the relay 16 to open. Thus the device is de-energized and the circuit is rearmed or reset, and now is in conditionto respondto-a new signal appliedto the circuit [1.

The pickup device It has its winding connected 110713118 input of arr-amplifier 23, the output of whichis connected to'a device 24. to be operated, such as .a, solenoid. In place of' amplifier 23 we may employ a suitable relay circuit.

When theadvancing end of-the.magnetized areagpasses the electromagnetic pickup device [3, the current induced inthe winding of. this device is-supplied to theampl-ifier 23,t0 provide amplified fiutput current. for operating the device 24. Device 24 -may be any suitablemechanism: operated'by a. current-pulse and SGIViIlg'tO perform any one. of various operations.

It will be evident that the time interval between application of a-signal to circuit H, and receipt of theresponse by- -device. 24,-will be a predetermmed valuedependent upon the rate of movement r the member In, and the distance :between devlfifisf Hand [3.

:netic device I i l4, it is erased, thus eliminating magnetization before being returned to the electromagnetic device ll.

In Figure 2 we have illustrated circuit means employing electronic amplifiers, in place of the relay type of circuit illustrated in Figure 1. Thus the si nal circuit 26 is shown connected to the input of amplifier 21 and the output of this amplifier connects with the winding of electromag- The signal is also shown being appliedto the electronic time delay means 29,

"which in turn is likewise connected to amplifier 21.

Amplifier 2'! is preferabl of the type which must be. restored for normal operation, after beingtripped by'application of a signal. The time delay means 29 is designed to supply such a re- .storing, pulse.- a. predetermined time interval after amplifier 21 has been operated by a signal.

Theelectromagnetic pickup device l2 in Figure 2 is shown connected to the input of amplifier 28, and the output of this amplifier. is likewise connected to apply av restoring pulse to the amplifier 21, for normal resetting-or rearming in the manner described with reference to Figure 1.

With the arrangement of Figure 2 it is presumed that after application of a signal, amp1i fier 21 energizes the electromagnetic device .H and continues such energization until a restoring pulse is applied. Normally the restoring pulse is applied'w-hen the advancing end of the magnetized areapasses the electromagnetic pickup device I2. If for some reason this restoring pulse isnot applied, then such a pulse is automatically applied by the means 29. It will be evident that this arrangement facilitates use in applications where the speed of movement of the member Hi is synchronized with some other mechanism,as' for example theforward speed of movement of an agricultural machine of the type disclosedandclaimed in Marihart application Serial No. 707,439 filed November 2, 1946. Assuming use with such a machine the current from amplifier 23 can be used to operate the clutch solenoid for effecting timed operation of the ground engaging cutters, and. the signal applied tocircuit 26 can be obtained from the photoelectric tube and amplifier means which is operated by light responses received. from growing plants. Normally-the time interval between energization of device H and the restoring of device, will be dependent upon the .speed of forward movement of the vehicle, which in turn determines the speed of movement of member it. However if device l2 together with amplifier 28 fails to effect restoration of the amplifier 21, then within a fixed time interval following energization of device I I, the system is; automatically rearmed.

Figure 3 illustrates a special type of circuit for controlling energization of device H. Thus inthis case two tubes BI and 32 of the thyratron type have their cathodes 33 connected together, and to one side of the output of amplifier 34. The control grid 36 for tube 3| is connected to the other side of the output from amplifier 34, through the condenser 31. The control grid 36 for tube 32 is connected to one side of the winding of electromagnetic pickup device l2, and the other side of this winding connects with thecathodes'33. A biasing battery 38 or other source of negative biasing voltage is shown connected in series with grid 36, and the grid of tube is connected to a source of negative bias through the resistor 39. The indicated source of anode current is connected between resistors 4i and 42.

'"When the magnetizedareapassesthe magnet 15 Resistor 4i connects with the anode 43 of, .the.

tube3| in series with the winding of device II, and resistor 42 connects directly with the anode of tube 32. Condenser 45 connects across the resistors 4| and 42.

The circuit of Figure 3 operates to energize the device responsive to application of a signal to the input 44 of the amplifier 34, and is restored by operation of the pickup device l2. Normally the tube 3| is nonconductive, and tube 32 is conductive. The grid 36 of tube 3| is normally negatively biased. Condenser 45 is charged because of the potential difierence applied to the same. Upon application of a signal to the input of amplifier 34, the grid of tube 3| is driven positive whereby the tube 3| is made conductive to cause current flow through the winding of device At the same time tube 32 is made nonconductive because condenser 45 momentarily causes the anode of the same to assume a potential negative relative to the cathode. The circuit is now disabled in that it will not respond to application of another signal. Tube 3| remains conductive until actuation of the electromagnetic pickup de- 4 vice I2. Current induced in the winding of device |2 places a positive potential upon the grid of tube 32 with the result that this tube is fired and becomes conductive, and whereby because of the action of condenser 45, tube 3| is extinguished. Thus device II is de-energiz-ed by actuation of the pickup device l2 and the circuit is rearmed to respond to the next signal.

The circuit illustrated in Figure 4 is similar to that of Figure 3, except that additional automatic means is employed for restoring the circuit after a predetermined period of time, .and irrespective of operation of device |2. Thusin this instance a condenser is connected between the cathodes 33, and each cathode is connected to the grounded side of the output of amplifier 34, through resistors 41.

Assuming that tube 3| is extinguished, and tub 32 conducting, condenser 46 is charged by virtue of the voltage across that resistor 41 which is connected to the cathode of tube 32. When the tube 3| is made conductive by a signal applied to circuit 44, and the tube 32 made nonconductive, condenser 46 starts to discharge through the resistors 41. The size of the condenser 46, and the values of the resistors 41, are selected so that condenser 46 is substantially completely discharged after a predetermined time interval. This time interval is selected so that it is somewhat longer in duration than the average time interval intervening between energization of device II, and responsive operation of the pickup device I2. When the condenser 46 looses its charge the tube 32 is fired and the tube 3| is extinguished. Thus the circuit is automatically rearmed.

It will be evident that the circuit arrangement of Figure 4 can be used to insure rearming of the circuit irrespective of whether or not the pickup device I2 is properly actuated.

The circuit illustrated in Figure 5 is a monostable type Eccles-Jordan multivibrator and makes use of triodes 5| and 52 or other suitable type of vacuum tube. The anode 53 of tube 5| is connected to the indicated source of plate current in series with the resistor 54 and the winding of device The plate 53 of tube 52 is connected to the source of plate current through the resistor 56. The grid 51 of tube 5| is connected to one side of the output of amplifier 34 in series with the rectifier 58. The cathode 59 of tube 5| is grounded and connected to the grid '6 of tube 5| through resistor 6|. Also a battery or other source of biasing voltage 62 is shown connected in series with the resistor 63 and across the output of amplifier 34.

The grid 51 of tube 52 is connected to the plate of tube 5| by resistor 64 and is also connected to ground through the resistor 65. One side of the winding of device |2 connects with the grounded side of the network and the other side connects through the coupling condenser 66 and rectifier 61, with the grid of tube 52. The cathode of tube 52 is grounded as indicated. A battery 68 or other source of biasing voltage is connected in series with the resistor 69, and from ground with the point of connection between condenser 66 and rectifier 61. Condenser 1| is connected between the grid of tube 5| and the plate of tube 52.

To explain operation of the circuit illustrated in Figure 5 it will be presumed that tube 5| is normally nonconductive while tube 52 is conductive. Assuming application of a signal to the circuit 44, the amplified signal component drives the grid of tube 5| from negative to positive, thus making this tube conductive to energize the winding of device I. At the time this tube is made conductive the grid of tube 52 becomes negative with respect to the cathode of this tube such that the tube becomes nonconductive. Immediately prior to receiving an actuating signal the condenser 1| is charged by virtue of the voltage difference applied to the same. When tube 5| becomes conductive and tube 52 nonconductive, due to application of a signal, condenser 1| starts to discharge.

When current is induced in the winding of device l2 by passage of the advancing end of the magnetized area, the grid of tube 52 is driven toward positive to make this tube conductive and the grid of tube 5| is in effect driven toward negative to render the same nonconductive.

The capacity of condenser 1| is such that normally it is not fully discharged by the time the circuit is rearmed by actuation of pickup device |2. If the pickup device fails to properly rearm the network then complete discharge of condenser 1| occurs with the result that the grid of tube 5| is made negative to thereby automatically make the tube 5| nonconductive, and tube 52 conductive.

Figure 6 schematically illustrates a mechanical device which can be used in connection with the invention. In this instance the member I0 is in the form of a thin flat disc made of suitable carbon steel. The magnetic devices I! and I4 are shown supported by an arm 12 which is carried by the fixed support 13. The devices I2 and i3 are mounted upon the arms 14 and 15 which can be angularly adjusted as indicated. While the arms 14 and 15 are in this instance shown mounted upon the same side of the disc 'IO, it should be understood that they can be mounted upon opposite sides to thereby increase the latitude of adjustment. The disc I0 is mounted upon a rotatable shaft 16 which can be driven from any suitable mechanism. As previously pointed out, the disc can be driven at a constant rate, or at a rate which may be varied from time to time as in the aforementioned Marihart agricultural machine.

In place of member ID being in the form of a disc as illustrated in Figure 6 it will be evident that it may be in the form of an endless band, tape or drum.

vWe claim:

1. In timingapparatus, acontinuously movable member of magnetizable material, anelectromagnetic device locatedzalong thepath of movement of said member and adapted when energized to efiect a, localized magnetization of saidmember, circuit means for efiecting energization of said electrical magnetic means, electromagnetic pickup means likewise located along the path of movement of said member and spaced from said first named electromagnetic device, said electromagnetic pickup means being responsive topassage of a localized magnetized region of said member, and means actuated by a response. from said electromagnetic pickup means for insuring rearming of said first .named circuit means.

2. In timing apparatus, -.an endless movable member of magnetizable material, an electromagnetic device located alongthe path of movement of said member and adapted when energized to efiect localized magnetization of said member, circuit means responsiveto a signal for efiecting energization of said electromagnetic device, said circuit means being. disabled to respond to subsequent signals until rearmed,.an electromagnetic pickup devicelocated along the path of movement ofsaidmember and spaced from said first named electromagnetic device, said electromagnetic pickup device being responsive to passage of a localized magnetized region past the same,.and means connecting said electromagnetic pickup device to first named circuit means and sewing to rearm first named circuit means responsive to actuation of said electromagnetic pickup device.

3. Timing apparatus as in claim 2 together with another electromagnetic pickup device located along the path of movement of ,said memher, and responsive to movement of a localized magnetized portion of said member past the same,

and magnetic means located in advance of said first named electromagnetic device for eradicating residual magnetization of said member before a portion of the same moves past said electromagnetic device.

4. In timing apparatus, an endless movable member of magnetizable material, an electromagnetic device located along the path of movement of said member and adapted when energized to efiect localized magnetization of said member, an electronic network responsive to a signal for effecting energization of said electromagnetic'device, said circuit serving to continue energization of said device after application of a signal and until application of a rearming pulse, an electromagnetic pickup device located along the path of movement of said member and spaced from said first named electromagnetic device, said pickup device being responsive to passage of a localized'magnetized region past the same, and circuit means connecting said pickup device to said first named circuit means whereby an induced'current pulse from said pickup device causes rearmingof said electronic circuit means.

5. Timing apparatus as .in claim 4 together with an-additional electromagnetic pickup device located along the path of movement of said member and responsiveto passage of a localized magnetized region past the same, and response means connected'to. said last named pickup device.

6. Timing apparatus as in claim 4 together with means incorporated in said electronic circuit to automatically restore the same'after'a predetermined time interval-following application of a signal.

7. In timing apparatus, an endless movable member of magnetizable material, an electromagnetic device located along the path of movement of said members and adapted when energized to efiect localized magnetization of said member, an electronic network responsive to a signal for-eifecting-energization of said electromagnetic device, said circuit serving to continue energization of said device after application of a signal and until rearming of the same, an electromagnetic pickup device located along. the path of movement of said memberandspaced from said first named electromagnetic device, said pickup devicebeing responsive to passage of a localized magnetized region past the same, response means operatively connected to said pickup device,'an'd means for automatically rearming saidelectronic circuit after a predetermined time interval following application of a signal.

8. In timing apparatus, an endless 'movable member of magnetizable material, an electromagnetic device located along the path of movement ofsaid member and adapted whenenergized to effect localized magnetization 'of said member, an electronic-- network responsive to-a signal'for effecting energization of said electromagnetic device, said circuit serving to continue energization of said device after application of a signal and until rearming of the same, an electromagnetic pickup device located along the path of movement of said member and spaced from said first named, electromagnetic device, said pickup device being responsive to passage of a localized magnetized-region past the same, response means operatively connected to said pickup device, and means for automatically rearming said electronic circuit means after an interval following energization of the first named electromagnetic device but before energization of the second named pickup device.

'WILLIAM R. HEWLETT. "DAVID PACKARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,370,133 Begun Feb. 27, 1945 2,370,176 Kornei Feb. 27,1945 2 ,378,383 'Arndt June 19, 1945 2,437,168 Marihart Mar. 2, 1948 

